Android高斯模糊、高斯平滑（Gaussian Blur）【2】

超、凢脫俗 2024-02-17 16:31 62阅读 0赞

**Android高斯模糊、高斯平滑（Gaussian Blur）【2】**

Android上的高斯模糊效果实现，策略不唯一，在github上有一个开源的实现算法：  
[https://github.com/paveldudka/blurring][https_github.com_paveldudka_blurring]  
性能上对附录参考文章【1】进行了改进和提升。  
Java代码：

package zhangphil.blur;
    
    import android.widget.ImageView;
    import android.widget.TextView;
    import android.annotation.TargetApi;
    import android.app.Activity;
    import android.graphics.Bitmap;
    import android.graphics.Canvas;
    import android.graphics.Paint;
    import android.graphics.drawable.BitmapDrawable;
    import android.os.Build;
    import android.os.Bundle;
    import android.view.View;
    import android.view.ViewTreeObserver;
    
    public class MainActivity extends Activity {
    	
    	private ImageView image;
    	private TextView text;
    
    	@Override
    	public void onCreate(Bundle savedInstanceState) {
    		super.onCreate(savedInstanceState);
    
    		setContentView(R.layout.activity_main);
    
    		image = (ImageView) findViewById(R.id.image);
    		text = (TextView) findViewById(R.id.text);
    		image.setImageResource(R.drawable.pic);
    		
    		applyBlur();
    	}
    
    	private void applyBlur() {
    		image.getViewTreeObserver().addOnPreDrawListener(new ViewTreeObserver.OnPreDrawListener() {
    			@Override
    			public boolean onPreDraw() {
    				image.getViewTreeObserver().removeOnPreDrawListener(this);
    				image.buildDrawingCache();
    
    				Bitmap bmp = image.getDrawingCache();
    				blur(bmp, text);
    				
    				return true;
    			}
    		});
    	}
    
    	
    	//为一个view增加一个以Bitmap bkg为底的高斯模糊图
    	@TargetApi(Build.VERSION_CODES.JELLY_BEAN)
    	private void blur(Bitmap bkg, View view) {
    		float scaleFactor = 1;
    		float radius = 20;
    		
    		//性能优先。如果换成这组数据,则速度明显提高
    		//	scaleFactor = 8;
    		//	radius = 2;
    
    		Bitmap overlay = Bitmap.createBitmap((int) (view.getMeasuredWidth() / scaleFactor),(int) (view.getMeasuredHeight() / scaleFactor), Bitmap.Config.ARGB_8888);
    		Canvas canvas = new Canvas(overlay);
    		canvas.translate(-view.getLeft() / scaleFactor, -view.getTop() / scaleFactor);
    		canvas.scale(1 / scaleFactor, 1 / scaleFactor);
    		Paint paint = new Paint();
    		paint.setFlags(Paint.FILTER_BITMAP_FLAG);
    		canvas.drawBitmap(bkg, 0, 0, paint);
    
    		overlay = FastBlur.doBlur(overlay, (int) radius, true);
    		
    		view.setBackground(new BitmapDrawable(getResources(), overlay));
    	}
    }

布局文件：

<?xml version="1.0" encoding="utf-8"?>
    <FrameLayout xmlns:android="http://schemas.android.com/apk/res/android"
        android:layout_width="match_parent"
        android:layout_height="match_parent" >
    
        <ImageView
            android:id="@+id/image"
            android:layout_width="match_parent"
            android:layout_height="match_parent"
            android:src="@drawable/pic" />
    
        <TextView
            android:id="@+id/text"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:layout_gravity="center"
            android:gravity="center"
            android:padding="5dip"
            android:text="Zhang Phil @ CSDN"
            android:textColor="@android:color/white"
            android:textSize="25sp"
            android:textStyle="bold" />
    
    </FrameLayout>

FastBlur.java工具类：

package zhangphil.blur;
    
    import android.graphics.Bitmap;
    import android.util.Log;
    
    public class FastBlur {
    	
    	public Bitmap fastblur(Bitmap sentBitmap, int radius) {
    
            // Stack Blur v1.0 from
            // http://www.quasimondo.com/StackBlurForCanvas/StackBlurDemo.html
            //
            // Java Author: Mario Klingemann <mario at quasimondo.com>
            // http://incubator.quasimondo.com
            // created Feburary 29, 2004
            // Android port : Yahel Bouaziz <yahel at kayenko.com>
            // http://www.kayenko.com
            // ported april 5th, 2012
    
            // This is a compromise between Gaussian Blur and Box blur
            // It creates much better looking blurs than Box Blur, but is
            // 7x faster than my Gaussian Blur implementation.
            //
            // I called it Stack Blur because this describes best how this
            // filter works internally: it creates a kind of moving stack
            // of colors whilst scanning through the image. Thereby it
            // just has to add one new block of color to the right side
            // of the stack and remove the leftmost color. The remaining
            // colors on the topmost layer of the stack are either added on
            // or reduced by one, depending on if they are on the right or
            // on the left side of the stack.
            //
            // If you are using this algorithm in your code please add
            // the following line:
            //
            // Stack Blur Algorithm by Mario Klingemann <mario@quasimondo.com>
    
            Bitmap bitmap = sentBitmap.copy(sentBitmap.getConfig(), true);
    
            if (radius < 1) {
                return (null);
            }
    
            int w = bitmap.getWidth();
            int h = bitmap.getHeight();
    
            int[] pix = new int[w * h];
            Log.e("pix", w + " " + h + " " + pix.length);
            bitmap.getPixels(pix, 0, w, 0, 0, w, h);
    
            int wm = w - 1;
            int hm = h - 1;
            int wh = w * h;
            int div = radius + radius + 1;
    
            int r[] = new int[wh];
            int g[] = new int[wh];
            int b[] = new int[wh];
            int rsum, gsum, bsum, x, y, i, p, yp, yi, yw;
            int vmin[] = new int[Math.max(w, h)];
    
            int divsum = (div + 1) >> 1;
            divsum *= divsum;
            int dv[] = new int[256 * divsum];
            for (i = 0; i < 256 * divsum; i++) {
                dv[i] = (i / divsum);
            }
    
            yw = yi = 0;
    
            int[][] stack = new int[div][3];
            int stackpointer;
            int stackstart;
            int[] sir;
            int rbs;
            int r1 = radius + 1;
            int routsum, goutsum, boutsum;
            int rinsum, ginsum, binsum;
    
            for (y = 0; y < h; y++) {
                rinsum = ginsum = binsum = routsum = goutsum = boutsum = rsum = gsum = bsum = 0;
                for (i = -radius; i <= radius; i++) {
                    p = pix[yi + Math.min(wm, Math.max(i, 0))];
                    sir = stack[i + radius];
                    sir[0] = (p & 0xff0000) >> 16;
                    sir[1] = (p & 0x00ff00) >> 8;
                    sir[2] = (p & 0x0000ff);
                    rbs = r1 - Math.abs(i);
                    rsum += sir[0] * rbs;
                    gsum += sir[1] * rbs;
                    bsum += sir[2] * rbs;
                    if (i > 0) {
                        rinsum += sir[0];
                        ginsum += sir[1];
                        binsum += sir[2];
                    } else {
                        routsum += sir[0];
                        goutsum += sir[1];
                        boutsum += sir[2];
                    }
                }
                stackpointer = radius;
    
                for (x = 0; x < w; x++) {
    
                    r[yi] = dv[rsum];
                    g[yi] = dv[gsum];
                    b[yi] = dv[bsum];
    
                    rsum -= routsum;
                    gsum -= goutsum;
                    bsum -= boutsum;
    
                    stackstart = stackpointer - radius + div;
                    sir = stack[stackstart % div];
    
                    routsum -= sir[0];
                    goutsum -= sir[1];
                    boutsum -= sir[2];
    
                    if (y == 0) {
                        vmin[x] = Math.min(x + radius + 1, wm);
                    }
                    p = pix[yw + vmin[x]];
    
                    sir[0] = (p & 0xff0000) >> 16;
                    sir[1] = (p & 0x00ff00) >> 8;
                    sir[2] = (p & 0x0000ff);
    
                    rinsum += sir[0];
                    ginsum += sir[1];
                    binsum += sir[2];
    
                    rsum += rinsum;
                    gsum += ginsum;
                    bsum += binsum;
    
                    stackpointer = (stackpointer + 1) % div;
                    sir = stack[(stackpointer) % div];
    
                    routsum += sir[0];
                    goutsum += sir[1];
                    boutsum += sir[2];
    
                    rinsum -= sir[0];
                    ginsum -= sir[1];
                    binsum -= sir[2];
    
                    yi++;
                }
                yw += w;
            }
            for (x = 0; x < w; x++) {
                rinsum = ginsum = binsum = routsum = goutsum = boutsum = rsum = gsum = bsum = 0;
                yp = -radius * w;
                for (i = -radius; i <= radius; i++) {
                    yi = Math.max(0, yp) + x;
    
                    sir = stack[i + radius];
    
                    sir[0] = r[yi];
                    sir[1] = g[yi];
                    sir[2] = b[yi];
    
                    rbs = r1 - Math.abs(i);
    
                    rsum += r[yi] * rbs;
                    gsum += g[yi] * rbs;
                    bsum += b[yi] * rbs;
    
                    if (i > 0) {
                        rinsum += sir[0];
                        ginsum += sir[1];
                        binsum += sir[2];
                    } else {
                        routsum += sir[0];
                        goutsum += sir[1];
                        boutsum += sir[2];
                    }
    
                    if (i < hm) {
                        yp += w;
                    }
                }
                yi = x;
                stackpointer = radius;
                for (y = 0; y < h; y++) {
                    // Preserve alpha channel: ( 0xff000000 & pix[yi] )
                    pix[yi] = ( 0xff000000 & pix[yi] ) | ( dv[rsum] << 16 ) | ( dv[gsum] << 8 ) | dv[bsum];
    
                    rsum -= routsum;
                    gsum -= goutsum;
                    bsum -= boutsum;
    
                    stackstart = stackpointer - radius + div;
                    sir = stack[stackstart % div];
    
                    routsum -= sir[0];
                    goutsum -= sir[1];
                    boutsum -= sir[2];
    
                    if (x == 0) {
                        vmin[y] = Math.min(y + r1, hm) * w;
                    }
                    p = x + vmin[y];
    
                    sir[0] = r[p];
                    sir[1] = g[p];
                    sir[2] = b[p];
    
                    rinsum += sir[0];
                    ginsum += sir[1];
                    binsum += sir[2];
    
                    rsum += rinsum;
                    gsum += ginsum;
                    bsum += binsum;
    
                    stackpointer = (stackpointer + 1) % div;
                    sir = stack[stackpointer];
    
                    routsum += sir[0];
                    goutsum += sir[1];
                    boutsum += sir[2];
    
                    rinsum -= sir[0];
                    ginsum -= sir[1];
                    binsum -= sir[2];
    
                    yi += w;
                }
            }
    
            Log.e("pix", w + " " + h + " " + pix.length);
            bitmap.setPixels(pix, 0, w, 0, 0, w, h);
    
            return (bitmap);
        }
    
    
    	public static Bitmap doBlur(Bitmap sentBitmap, int radius,
    			boolean canReuseInBitmap) {
    
    		// Stack Blur v1.0 from
    		// http://www.quasimondo.com/StackBlurForCanvas/StackBlurDemo.html
    		//
    		// Java Author: Mario Klingemann <mario at quasimondo.com>
    		// http://incubator.quasimondo.com
    		// created Feburary 29, 2004
    		// Android port : Yahel Bouaziz <yahel at kayenko.com>
    		// http://www.kayenko.com
    		// ported april 5th, 2012
    
    		// This is a compromise between Gaussian Blur and Box blur
    		// It creates much better looking blurs than Box Blur, but is
    		// 7x faster than my Gaussian Blur implementation.
    		//
    		// I called it Stack Blur because this describes best how this
    		// filter works internally: it creates a kind of moving stack
    		// of colors whilst scanning through the image. Thereby it
    		// just has to add one new block of color to the right side
    		// of the stack and remove the leftmost color. The remaining
    		// colors on the topmost layer of the stack are either added on
    		// or reduced by one, depending on if they are on the right or
    		// on the left side of the stack.
    		//
    		// If you are using this algorithm in your code please add
    		// the following line:
    		//
    		// Stack Blur Algorithm by Mario Klingemann <mario@quasimondo.com>
    
    		Bitmap bitmap;
    		if (canReuseInBitmap) {
    			bitmap = sentBitmap;
    		} else {
    			bitmap = sentBitmap.copy(sentBitmap.getConfig(), true);
    		}
    
    		if (radius < 1) {
    			return (null);
    		}
    
    		int w = bitmap.getWidth();
    		int h = bitmap.getHeight();
    
    		int[] pix = new int[w * h];
    		bitmap.getPixels(pix, 0, w, 0, 0, w, h);
    
    		int wm = w - 1;
    		int hm = h - 1;
    		int wh = w * h;
    		int div = radius + radius + 1;
    
    		int r[] = new int[wh];
    		int g[] = new int[wh];
    		int b[] = new int[wh];
    		int rsum, gsum, bsum, x, y, i, p, yp, yi, yw;
    		int vmin[] = new int[Math.max(w, h)];
    
    		int divsum = (div + 1) >> 1;
    		divsum *= divsum;
    		int dv[] = new int[256 * divsum];
    		for (i = 0; i < 256 * divsum; i++) {
    			dv[i] = (i / divsum);
    		}
    
    		yw = yi = 0;
    
    		int[][] stack = new int[div][3];
    		int stackpointer;
    		int stackstart;
    		int[] sir;
    		int rbs;
    		int r1 = radius + 1;
    		int routsum, goutsum, boutsum;
    		int rinsum, ginsum, binsum;
    
    		for (y = 0; y < h; y++) {
    			rinsum = ginsum = binsum = routsum = goutsum = boutsum = rsum = gsum = bsum = 0;
    			for (i = -radius; i <= radius; i++) {
    				p = pix[yi + Math.min(wm, Math.max(i, 0))];
    				sir = stack[i + radius];
    				sir[0] = (p & 0xff0000) >> 16;
    				sir[1] = (p & 0x00ff00) >> 8;
    				sir[2] = (p & 0x0000ff);
    				rbs = r1 - Math.abs(i);
    				rsum += sir[0] * rbs;
    				gsum += sir[1] * rbs;
    				bsum += sir[2] * rbs;
    				if (i > 0) {
    					rinsum += sir[0];
    					ginsum += sir[1];
    					binsum += sir[2];
    				} else {
    					routsum += sir[0];
    					goutsum += sir[1];
    					boutsum += sir[2];
    				}
    			}
    			stackpointer = radius;
    
    			for (x = 0; x < w; x++) {
    
    				r[yi] = dv[rsum];
    				g[yi] = dv[gsum];
    				b[yi] = dv[bsum];
    
    				rsum -= routsum;
    				gsum -= goutsum;
    				bsum -= boutsum;
    
    				stackstart = stackpointer - radius + div;
    				sir = stack[stackstart % div];
    
    				routsum -= sir[0];
    				goutsum -= sir[1];
    				boutsum -= sir[2];
    
    				if (y == 0) {
    					vmin[x] = Math.min(x + radius + 1, wm);
    				}
    				p = pix[yw + vmin[x]];
    
    				sir[0] = (p & 0xff0000) >> 16;
    				sir[1] = (p & 0x00ff00) >> 8;
    				sir[2] = (p & 0x0000ff);
    
    				rinsum += sir[0];
    				ginsum += sir[1];
    				binsum += sir[2];
    
    				rsum += rinsum;
    				gsum += ginsum;
    				bsum += binsum;
    
    				stackpointer = (stackpointer + 1) % div;
    				sir = stack[(stackpointer) % div];
    
    				routsum += sir[0];
    				goutsum += sir[1];
    				boutsum += sir[2];
    
    				rinsum -= sir[0];
    				ginsum -= sir[1];
    				binsum -= sir[2];
    
    				yi++;
    			}
    			yw += w;
    		}
    		for (x = 0; x < w; x++) {
    			rinsum = ginsum = binsum = routsum = goutsum = boutsum = rsum = gsum = bsum = 0;
    			yp = -radius * w;
    			for (i = -radius; i <= radius; i++) {
    				yi = Math.max(0, yp) + x;
    
    				sir = stack[i + radius];
    
    				sir[0] = r[yi];
    				sir[1] = g[yi];
    				sir[2] = b[yi];
    
    				rbs = r1 - Math.abs(i);
    
    				rsum += r[yi] * rbs;
    				gsum += g[yi] * rbs;
    				bsum += b[yi] * rbs;
    
    				if (i > 0) {
    					rinsum += sir[0];
    					ginsum += sir[1];
    					binsum += sir[2];
    				} else {
    					routsum += sir[0];
    					goutsum += sir[1];
    					boutsum += sir[2];
    				}
    
    				if (i < hm) {
    					yp += w;
    				}
    			}
    			yi = x;
    			stackpointer = radius;
    			for (y = 0; y < h; y++) {
    				// Preserve alpha channel: ( 0xff000000 & pix[yi] )
    				pix[yi] = (0xff000000 & pix[yi]) | (dv[rsum] << 16)
    						| (dv[gsum] << 8) | dv[bsum];
    
    				rsum -= routsum;
    				gsum -= goutsum;
    				bsum -= boutsum;
    
    				stackstart = stackpointer - radius + div;
    				sir = stack[stackstart % div];
    
    				routsum -= sir[0];
    				goutsum -= sir[1];
    				boutsum -= sir[2];
    
    				if (x == 0) {
    					vmin[y] = Math.min(y + r1, hm) * w;
    				}
    				p = x + vmin[y];
    
    				sir[0] = r[p];
    				sir[1] = g[p];
    				sir[2] = b[p];
    
    				rinsum += sir[0];
    				ginsum += sir[1];
    				binsum += sir[2];
    
    				rsum += rinsum;
    				gsum += ginsum;
    				bsum += binsum;
    
    				stackpointer = (stackpointer + 1) % div;
    				sir = stack[stackpointer];
    
    				routsum += sir[0];
    				goutsum += sir[1];
    				boutsum += sir[2];
    
    				rinsum -= sir[0];
    				ginsum -= sir[1];
    				binsum -= sir[2];
    
    				yi += w;
    			}
    		}
    
    		bitmap.setPixels(pix, 0, w, 0, 0, w, h);
    
    		return (bitmap);
    	}
    }

处理前的图片pic.png：

![Center][]

代码运行结果：

![Center 1][]

附录参考文章：  
【文章1】《Android高斯模糊、高斯平滑（Gaussian Blur）【1】》链接地址：[http://blog.csdn.net/zhangphil/article/details/49981499][http_blog.csdn.net_zhangphil_article_details_49981499]

[https_github.com_paveldudka_blurring]: https://github.com/paveldudka/blurring
[Center]: https://image.dandelioncloud.cn/pgy_files/images/2024/01/30/d3293c5312f449ff868d7fc135986eec.png
[Center 1]: https://image.dandelioncloud.cn/pgy_files/images/2024/01/30/001ae584e146497fb518927059f78e24.png
[http_blog.csdn.net_zhangphil_article_details_49981499]: http://blog.csdn.net/zhangphil/article/details/49981499